To elucidate the mechanisms responsible for the salt and water retention in congestive failure we propose to compare the response of the afferent and efferent pathways responsible for the tachycardia and hypertension induced by mild pulmonary stenosis; compare the response of the renin-angiotensin-aldosterone system, ADH and the autonomic nervous system during the induction of congestive failure in the conscious dog by inferior vena caval constriction, pulmonary artery stenosis, and, aortic stenosis; study renin granule formation and release in the rabbit ear chamber; induce acute heart failure in rats by coronary ligation and to measure changes in renin, aldosterone, and renal Na-K-ATPase activity during the first few postsurfical days; and finally acute heart failure in Brattleboro strain rats by coronary ligation and to determine whether the compensatory responses in the absence of antidiuretic hormone differ from those observed in normal rats.